What are the contributions renewable energy sources can make to achieving our environmental commitments? What needs to be done to support the infrastructure required?
We have limited reserves of fossil fuels. In principle at least, there is international agreement that we need to move off carbon and on to renewable energy sources. Yet there is still great debate about how this can be achieved. Although they provide 18 per cent of electricity generation worldwide, renewables' share of electricity has struggled to keep pace with overall demand growth for power.
The term "renewables" refers to electricity that comes from naturally replenished resources such as sunlight, wind and geothermal heat. It can also refer to biofuels and hydrogen. In theory, if methods of turning these into energy are perfected, we need never face another fuel crisis.
So, what's the problem? One criticism often levelled at wind and solar power is that they are variable or intermittent. There are also "not in my backyard" concerns relating to the visual impact of wind turbines. In the UK, planning laws can be a hindrance to increasing the use
of wind turbines. On the other hand, there are benefits to local generation, as it contributes to the flexibility of the system and its resistance to central shocks.
Methods of storage are still expensive, and in these austere times there is a risk that investment in improving the technology around renewable energy will not be given priority. However, there is a strong argument in favour of boosting what Nick Clegg has called "the green economy" as a way to tackle climate change and to create jobs.
Renewable energy usually gets cheaper with time, even as we see fossil fuels getting more expensive. A report by the International Energy Agency this year was optimistic about this cost-reduction trend for the sector continuing, arguing that, increasingly, renewable energy presents "investment opportunities without the need for specific economic support".
It would benefit the planet, and not just the world economy, if effort were put into making renewables viable for the future.